I've toyed with this, and was unsure. There are many places where the "Standard" room is not available for 3,so if you search for an award for a party of 3 you are SOL. You can find a room for 2, book a standard award and upgrade to a suite that accommodates 3. However, I expected to pay extra if I added a 3rd person later, since the rates when booking cash for 3 are higher than 2. Just an example would be Andaz London shows a $100 price increase for the Andaz Suite if you book for 2 vs 3.

Glad to know some think its ok with no extra cost, but if it were me, I would not be surprised to be asked to pay something extra. Hope it works out!